1. Field of the Invention
The present invention relates generally to a detection apparatus based on ion mobility principles for trace detection, and in particular to an ion mobility tube.
2. Description of the Related Art
The ion mobility tube is a core part of a detection apparatus based on the ion mobility principles. It generally comprises an ionization source chamber, an ion door, a mobility region, a constraining grid, and a Faraday disk. The above components of a conventional ion mobility tube are formed by means of separate metal electrode sheets. The electrode sheets are separated from each other by insulating material. The metal electrode sheets are connected to an external cable or separate divider resistors are welded between the metal electrode sheets, or divider resistors are disposed outside the ion mobility tube. Such an ion mobility tube has a complicated structure with many lead wires, and cannot be easily detached since two electrode sheets are welded to each other through wires or electronic elements. In addition, all the structures such as the ion door and the constraining grid are made of thin net-shaped or wire-shaped metal and thus have a bad strength in the conventional ion mobility tube. Change in performance caused by deformation is considerable, therefore accuracy of detection of the ion mobility tube is degraded.